Conventionally, scattered-light methods are used for measuring the concentration of particles in exhaust gases and other colloids.
A measuring device provided for such a purpose usually includes a high-power light source such as a laser, which radiates light into a measuring chamber through which the colloid to be measured is routed. At least one light sensor, which detects light that has been scattered by particles present in the colloid, is allocated to the measuring chamber. In order to check the proper functioning of such a measuring device and to calibrate the measuring device, it is necessary to adjust a defined state in the measuring chamber in which the irradiated light is scattered in a defined and known manner. Measuring devices that are used for official measurements are subject to an obligatory calibration which further increases the need for supplying precise measuring results with high reliability. Such a measuring device in described in German Patent Application No. 10 2010 002423.6.